LR Question 21 Explanation
QUESTION TEXT: Most of the students who took Spanish 101 at the…
QUESTION TYPE: Must be True
FACTS:
- Most Spanish 101 students attended every class.
- Every student who scored lower than B-minus missed at least one class.
ANALYSIS: This is a mathematical question, and it tests how intuitively you understand the word “most”. Let’s say there were 9 students. “Most” of them would be five or more.
All the students who scored below B-minus missed at least one class. What’s the largest number that could have done this? Four. That’s because at least five students (“most”) did attend every class.
This lets us conclude that at least five students scored b-minus or above. So “most” students scored b-minus and above.
Note the subtle differences in wording. It’s easy to misread this question as saying that every student who scored b-minus or below missed a class. But the question doesn’t say that….instead, it says every student who scored below b-minus missed class.
___________
- We don’t know anything about students who scored A-minus or higher. Maybe only one student did that? (And the “most students” who attended classes all scored a B-plus)
- This doesn’t have to be true. It could be that only one student scored below b-minus, and 1,000 other students scored b-minus or above.
- This is very tempting, and similar to E. Notice that the stimulus says every student who received a grade below a b-minus missed a class.
That doesn’t include students who scored exactly a b-minus. So this answer should have said “scored b-minus or higher”. - This doesn’t have to be true. Maybe all students who got b-minus or above attended every class. “most” can go as high as “all”.
- CORRECT. See the analysis for a full explanation. If most students attended all classes, then “most” students must have scored b-minus or above. Because no student who scored below b-minus had perfect attendance.
More Resources for Must Be True Questions
- Conditional Reasoning Article: Learn about conditional statements on the LSAT.
- LR Diagrams Guide: Learn how to draw LR diagrams.
- Intro to Conditional Reasoning: This intro course lesson covers conditional reasoning basics.
- Intro Course lesson: This intro course lesson covers Must Be True questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers must be true questions.
Frustrated. What kind of assumptions do we need to make? Let’s say there are 1000 students at this university and 9 take Spanish 101; most of the 9 (5 or more) attended every class. Now a separate premise which states ALL the students who scored below B-minus missed at least one class. How can we infer that more than half (501 or more students) recivied B-? Or do we assume that we are only talking about students who took Spanish 101? My brain is melting.
As a general rule, you shouldn’t be assuming anything beyond the letter of the stimulus — unless it’s a very common sense assumption (a common sense definition of a word for example).
The first sentence indicates that we’re not talking about the school in general. It specifically refers to those students who took Spanish 101. I’d argue that the second sentence is also very clearly referring to just those students who took Spanish 101. Think of it this way, read the first sentence, and then read the second sentence as “However, each student at the university who received a grade lower than B-…”. It sounds awkward and doesn’t follow from the first sentence because of the word “however”.
“However” is modifying the content of the first sentence. Although most of the students in Spanish 101 attended every class, those who received lower than a B- missed at least one class.
Thanks, that makes sense, and as a side note, all this helps.
No problem Kim! Happy to help.
I am still struggling with the same concept as Kim. How do we know that we are EXCLSUIVELY speaking about students who take Spanish101 and not students of the school writ large?
Good question. As Lucas said, the word However bridges together the two sentences and shows that the second sentence is still talking about the same group. Likewise the parallel reference to class sessions is another clue.
Note: This is an old comment but I wanted to clarify the point.
I understand why E is correct; however, I am having trouble seeing why B is incorrect, It seems like if most students who missed at lease one class session received a grade lower than a B minus is restated the sentence “Each student who received a grade lower than a B minus missed at least one class session”. Could you provide further detail on why B is incorrect?
Here’s what we know from the stimulus:
Less than B- –> Missed at least one class
(B) is reversing the logic of the premise. It’s saying:
Missed at least one class MOST Grade < B- But we don't know if (B) is true. Let's say 60% of students went to every class, leaving 40% who missed at least one class. What if only 10% of those 40% received a grade less than B- ? What if the remaining 30% of students who missed at least one class (100% - 60% - 10% = 30%) got a B or up? That would mean that most students who missed at least one class received a grade higher than B-.
It’s important to be aware of the direction of the arrows in the stimulus’ conditional reasoning. We know something for sure about those who received a grade less than B-, but we don’t know something for certain about those who missed at least one class (no arrow pointing away from that condition).
I think one of the sentences in the analysis is incorrect. You state above: “All the students who scored below B-minus missed every class. What’s the largest number that could have done this? ” But the stimulus says, “… each student who received a grade lower than B minus missed at least one class session.” (not “every class”)
It’s a small point, but I was confused by it while reading through the analysis, so it’s possible others will be, as well.
Thanks for catching this! The page has been updated.
Hi, I was wondering whether anyone could explain why E is correct.
I was not sure about E because it says more than half of the students received a grade of B-or higher, but I thought it’s not nec, true because there might be other factors influenced their grades, such as test score etc. Even though some students attend all classes, they might have done poorly on exams and it might result in receiving grades lower than B-, so I thought E cannot be inferred from the stimuli, especially the part “more than half…” at least some, maybe, but more than half is too much.
Could anyone explain this question?:(
The first statement of the stimulus tells us that most of the students who took Spanish 101 attended every class session. That means 51-100% of the students attended every class (let’s call these students Group 1).
The stimulus also tells us that everyone who received a grade lower than B- missed at least one class. That means that no one in Group 1 received lower than a B- (because they all attended every class.) So, 51-100% of the students definitely did not receive lower than a B-. We can also express that as Group 1 must’ve received a score of B- or higher.
(E) is therefore correct, because Group 1 (more than half of students) received a grade of B- or higher.